Silicon (Si), gallium arsenide (GaAs), and the like, are conventionally known as a semiconductor material. Recently, the field of use of a semiconductor element is rapidly expanding. The semiconductor element is accordingly more often used under severe environments such as a high temperature environment. Therefore, achievement of a semiconductor element that is able to withstand a high temperature environment is one of important problems from the viewpoint of a reliable operation, processing of a large amount of information, and improvement in the controllability in wide ranges of applications and environments.
Silicon carbide (SiC) is of interest as one of materials that can be used for manufacturing a semiconductor element having an excellent heat resistance. SiC has an excellent mechanical strength and a radiation hardness. Moreover, adding impurities to SiC enables a valence electron such as an electron or a hole to be easily controlled, and SiC is characterized in a wide band gap (about 2.93 eV in 6H single crystal SiC; 3.26 eV in 4H single crystal SiC). This is why SiC is expected as a material for a next-generation power device that achieves a high-temperature resistance, high frequency resistance, high voltage resistance, and high environment resistance, which cannot be achieved by the existing semiconductor material described above. Methods for manufacturing a semiconductor material using SiC are disclosed in Patent Documents 1 to 3.
Patent Document 1 discloses a method for manufacturing a SiC semiconductor having high quality, when generation of SiC polycrystalline is suppressed by uniformizing the temperature in a growth furnace causing a growth of a seed crystal. Patent Document 2 discloses a method for manufacturing a SiC semiconductor having little defect and high quality by forming a plurality of recesses in a seed crystal.